The body of Mohammed Abu Khder, 16, was found in Jerusalem’s forest area. His death followed the murder of three Israeli youths. Picture: AFP/FAMILY HANDOUT ===Source:AFP

An Israeli army spokesman on Tuesday confirmed an air operation code-named Protective Edge had been launched, but did not give details.

Several houses were targeted in the raids on the southern Gaza Strip, notably in Khan Yunes, witnesses said.

Israel had “crossed a red line by attacking houses”, warned the Ezzedine al-Qassam Brigades, the armed wing of the Islamist Hamas movement which has its stronghold in Gaza.

“If this policy does not stop we will respond by enlarging the radius of our targets to the point where the enemy will be surprised,” it said in a statement.

Mothers of two of the three Israeli teens who were abducted and killed in the occupied West Bank mourn during the joint funeral of their sons in the Israeli city of Modiin earlier this month. Picture: APSource:AP

Asma weeps at the funeral of her brother, Gomha Abu Shalouf, 27, a member the military wing of Hamas, who was killed in an air strike in Rafah, southern Gaza Strip on Monday, July 7, 2014. Picture: APSource:AP

Israeli warplanes launched dozens of air strikes in the Gaza Strip on Thursday. Picture: AFPSource:AFP

The Israeli military said on Monday more than 40 rockets had been fired at the south within a short period.

Sirens were heard in 10 locations, including in Beit Shemesh about 80km from the Gaza Strip, a military statement said.

About 16 rockets struck the area around the southern city of Beersheva, 40km from Gaza. Beersheva is home to 200,000 people.

The Ezzedine al-Qassam Brigades claimed responsibility for the attacks.

The mother of Tariq Abu Khder (on iPad), the cousin of the murdered Palestinian youth Mohammed Abu Khder, shows a picture of her son who she alleges was assaulted by Israeli border police in East Jerusalem on July 5, 2014. Picture: AFPSource:AFP

Shortly after, Israeli planes hit more than 30 targets near the southern Gaza city of Rafah in an area close to the Israeli border which is riddled with tunnels, Palestinian witnesses and security sources told AFP.

Israel’s Channel 1 television said the attacks came after the security cabinet gave the military a green light to “toughen the response to Hamas”.

The channel also showed footage of dozens of tanks massing near the border with Gaza, preparing for a possible offensive against the enclave.

The latest flare-up came a day after Israel arrested six Jewish extremists in connection with the killing of the Palestinian teenager, who was kidnapped and burnt to death in a suspected revenge crime after last month’s abduction and murder of three Israeli youths in the West Bank.

The July 2 killing sparked five days of violent clashes in annexed east Jerusalem and in Arab towns across Israel, with police arresting hundreds of people.

The killing has caused shock, outrage, and no small measure of shame in Israel.

“To take a young boy, to kill him, to burn him — what for?” asked outgoing President Shimon Peres.

On Monday, both Peres and Prime Minister Benjamin Netanyahu called the teenager’s father to convey their condolences and express outrage over the murder.

“I am ashamed on behalf of my nation and grieve with you,” Peres said, while Netanyahu condemned the murder as “abhorrent”.

Overnight, the angry protests which have gripped east Jerusalem and Arab Israeli towns continued to spread, with police arresting 110 people.